The E32 enhancer trap insertion at the Dmel decapentaplegic (dpp) locus. Gene models are colored by predicted core promoter type as in Fig. 2. Two transcript isoforms are shown for dpp because this gene has different core promoter predictions for two of its major transcription start sites (other dpp start sites are not shown, see St Johnston et al. 1990). The HCNE-spanned gene desert downstream from dpp contains several conserved enhancers that specify dpp expression in imaginal discs (Merli et al. 1996). Although the neighboring, divergently transcribed genes SLY1 homologous (Slh) and out at first (oaf) are insensitive to the array of dpp enhancers and have different expression patterns, the enhancer trap insertion E32, inserted into the 5′-untranslated region of oaf (arrow), reproduces part of the dpp expression pattern in imaginal discs (Merli et al. 1996). Five other genes (underlined) are in conserved microsynteny with dpp, Slh, and oaf among the investigated flies.
